#define _CRT_SECURE_NO_WARNINGS 1 

#include<iostream>
#include<algorithm>

using namespace std;

int main()
{
	int n;
	cin >> n;
	int res = n;
	while (n >= 3)
	{
		res += n / 3;
		n = n /3 + n % 3;
	}
	cout << res << endl;
	return 0;
}